1. Field of the Invention
The present invention relates to a nailing machine, such as a pneumatic nailing machine, in which a part constituting a nose is improved so as to increase the service life of a driver blade for driving a nail.
2. Background Art
As well known, a nailing machine operates such that the driver blade is driven to move at high speed by the utilization of pressure of compressed air or the like, and the nailing machine drives a nail into an object to be worked. In the case of driving nails having round heads, which are connected by plastics or a wire, it is a common practice that the cross section of the driver blade is configured to be crescent or semicircular so as to avoid driving the adjacent nail.
Great impact force acts on the driver blade (referred simply to as “blade”). In the case of a blade having such a configured cross section, the gravity center of the blade is not aligned with the center line of the piston. The result is that a great bending is apt to occur in the blade. Due to this, the blade inevitably contacts with the nose hole surface. In this case, the metal surfaces contact each other at high speed. The contact surfaces are heated to be several hundreds degrees Celsius or higher locally, and alteration layers are formed in the surface regions of both the surfaces. In the blade, minute cracks are formed in the alteration layer and grow into fatigue fracture. The result is that the product service life is reduced. There is an approach to solve the problem in which the nose part is made of a sintered metal and impregnated with oil. However, it is the present state that the solution provided by this approach is still unsatisfactory.